So his body (body of the Sword God), under the superiority of Rule of Swords skill, saw the magic talent the Dragon God gave him as interference to his body and blocked it out. Kinda like White Blood cells blocking out foreign matter. Huh…

Is that what they meant? I couldn’t understand at all. It feels as though he has the skill to use magic but for some techicality in another skill he can’t. And Soma isn’t bothered because he can eventually learn to do magic? Is it a matter of effort or is it just he has to find a way to break down the wall his skill is putting up?

I want to have your child so I reincarnated you as a human and myself as an elf. I will mature in 500 years lets have a child then.
Soma: *facepalm*
Human life expectancy: about 150 max
500 years – she can have children and he will be long dead.

神域の器: I understood this as god-tier or divine-tier weapon.
万魔(man ma)の剣: could also be understood as sword of mana or sword of ten thousand magic
Six Poetry Immortals (六歌仙): If it is in the skill list, it most likely means a noble’s cultivation in poetry and music.

Vessel of God’s Sanctuary sounds like his physical body is the Avatar of the Sword God, which is him. Sword of Ten Thousand Demons sounds like an ultimate attack. Six Poetry Immortals may be the path his Godhood Takes.